1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same.
2. Description of the Related Art
Recent high-speed switching diodes require fast switching characteristics and soft recovery characteristics.
Since a common PN-junction diode in the field of diodes uses minority carriers, a forward voltage may be lowered due to a conductivity modulation effect.
However, high-speed switching characteristics are deteriorated due to reverse recovery caused by the minority carriers.
When a reverse voltage is rapidly applied to a PN junction diode while a forward current is flowing therein, a high-level reverse current flows instantly, since minority carriers injected from a PN junction move in reverse, and reverse recovery characteristics refer to a current flowing until the minority carriers flow out or are extinct.
A high-speed switching diode may shorten the time taken for the reverse current to reach 0 (time of reverse recovery: trr) and have soft recovery characteristics by smoothening a reverse current waveform.
High-speed switching diodes are largely classified into a fast recovery diode (FRD), a high-efficiency diode (HED), and a schottky barrier diode (SBD).
A FRD has the same structure as a general PN diode, but is a diode in which minority carriers are quickly extinct after turn-off by diffusing impurities such as platinum, gold, and the like in silicon through electrons or neutron beam irradiation to increase recombination of electrons and holes.
In the related art, a P− type active layer of the FRD is formed by injecting and diffusing P type impurities.
In addition, a separate space is needed to apply a field limiting ring for maintaining the withstand voltage of a device.
A device requiring a high withstand voltage requires more space, leading to an increase in chip size.
In particular, in the case that the space for applying the field limiting ring thereto is wider, an active area of the device may be narrower.
Since the active area in which devices operate may be further reduced due to miniaturization and higher degrees of integration of existing types of electronic equipment or electronic devices, it is necessary to maintain the withstand voltage and secure the active area.
Patent Document 1 of Related Art Document below discloses an invention relating to a PIN diode.
Patent Document 1 discloses a semiconductor device including a predetermined film having crystal defects formed in an anode or a cathode.
However, the invention described in Patent Document 1 has a disadvantage in that since the predetermined film is in contact with the anode or the cathode, the withstand voltage is not maintained in the contact area.
Therefore, the invention disclosed in Patent Document 1 fails to prevent forward voltage drop, and is different from the present invention in view of the constitution and effects thereof.
Patent Document 1 is directed to a power semiconductor device.
However, it fails to disclose a field limiting ring formed inside a P type semiconductor area.